This invention relates to an induction system for an internal combustion engine and more particularly to an induction system for improving low-speed running performance.
The difficulties with obtaining smooth running, good fuel economy and effective emission control at idle or low-speed with internal combustion engines is well-known. One of the main reasons for these difficulties is the slow-flame travel which is experienced in the combustion chamber under these circumstances. This problem is aggravated by the slow speed at which the charge passes through the induction system under these running conditions, which tends to cause condensation of fuel in the intake passages and which aggravates the slow-speed running problems aforenoted. In order to overcome these difficulties, it has been proposed to provide a relatively small auxiliary induction passage through which the intake charge is delivered to the combustion chambers during idle and slow-speed running. This arrangement has been found to greatly improve slow-speed running, fuel economy and emission control. With such arrangements, however, it has been found that the speed at which the intake charge passes through the auxiliary induction passage is still retarded due to the restricted pressure at the upstream side of this passage.
It is, therefore, a principal object of this invention to provide an improved induction system for an internal combustion engine.
It is another object of the invention to provide an induction system for an internal combustion engine that improves slow-speed running characteristics.
It is a still further object of the invention to provide an auxiliary induction system for slow-speed running of an internal combustion engine that accommodates greater airflows.